Drop django_openstack_auth from requirements.txt
Drop django_openstack_auth from requirements.txt

django_openstack_auth has been merged into horizon tree
as an effort of blueprint merge-openstack-auth.
There is no need to depend on django_openstack_auth any more.

Change-Id: Ifecbe219e5f193bfc35df370691b9cc0ee6097b2

openstack/sahara-dashboard,openstack/sahara-dashboard,openstack/sahara-dashboard,openstack/sahara-dashboard